83 research outputs found
On the set of robust sustainable thresholds
No full textIn natural resource management, or more generally in the study of sustainability issues, the objective often consists in maintaining the state of a given system within a desirable configuration, typically established in terms of standards or thresholds. For instance, in fisheries management, the procedure of designing policies may include keeping the spawning stock biomass over a precautionary threshold and also ensuring minimal catches. Whenever the evolution of some natural resources, under the action of controls and un- certainties, is represented by a dynamical system in discrete-time, the aim of this paper is to characterize the set of robust sustainable thresholds. That is, the thresholds for which there exists a trajectory satisfying, for all possible uncertainty scenarios, prescribed constraints parametrized by such thresholds. This set provides useful information to users and decision-makers, illustrat- ing the trade-offs between constraints. Using optimal control, maximin and level-set approaches, we characterize the weak Pareto front of the set of robust sustainable thresholds and derive a numerical method for computing the en- tire set, as we show with a numerical example relying on renewable resource management
A continental biomass stock and stock exchange estimation approach for Australia.
No full textTo implement Australia's National Carbon Accounting System it is necessary to estimate biomass stock, continentally, and change in stock, at a sub-hectare spatial resolution. The approach developed to meet this requirement is a hybrid between GIS-based process modelling and empiricism. Multi-temporal mapping of productivity was carried out using a variant of the 3PG (physiological principles predicting growth) model. Relationships were found between mapped productivity indices and measurements of biomass at maturity (i.e. long-term-undisturbed stands). This information was then used to interpolate maps of biomass potential. Simple growth formulae were used to plot biomass accumulation, with the 'rate of approach to mature biomass' set by the age at which maximum current annual increment occurs and the predicted site plant productivity over time. The age of the forest stand was determined from disturbance events detected by twelve national coverages of Landsat MSS, TM and ETM+ remotely-sensed data collected between 1972 and 2002. Responses to thinning of existing forests are calculated using an adjustment of stand age concurrent with the intensity of the thinning event
Figuraciones y signos. Num. 9 Año 3 (2000) mayo-agosto. Alquimia. Sistema Nacional de Fototecas
No full text- La caja de Pandora - A quien corresponda, por Francisco Hernández - ¿Histeria o melancolía?, por Roger Bartra - Cuerpos con memoria ojos que los miran, por Patricia Fajer Camus - Villa en la silla presidencial, por José de la Colina - De la belleza del cuerpo masculino, por Horacio Franco - Obregón y su legado, por Luis Gonzáles de Alba - Dos observaciones sobre el paisaje de Mil Cumbres, por Jan Hendriz - Retrato de padre e hija, por Yishai Jusidman - Dos minutos de microhistoria, por David Huerta - Mujeres en el tranvía, por José Emilio Pacheco - Presagio de la muerte anónima, por Jorge Juanes - María Zavala "la destroyer" ayudo a bien morir a los soldados, por Pablo Ortiz Monasterio - La Bella Unión, por Aureilo de los Reyes - Tumba 59, por Irma Palacios Flores - Francisco Villa llorando, por Ruggiero Romano - Tres turistas en Veracruz, por Ana García Bergua - Hombre kickapú, por Alfredo López Austin - El cielo y la claridad, la tierra y las tinieblas, por Juan Fontcuberta - La dama del perrito, por Cristopher Domínguez Michael - La mujer frente al tribunal, por Carla Rippey - Una forma de memoria, por Gerardo Suter - Los carros del Templo Mayor, por Eduardo López Moctezuma - La fotografía en Michoacán, por Guadalupe Carbajal y Agripina Alfaro Trujillo - Una sobreviviente memoria fotográfica: Dolores Casasola, por Rebeca Monroy Nasr - Polvo de aquellos lodos, por Georgina Rodríguez Hernández - Normas catalográficas del Sistema Nacional de Fototecas del INAH, por Fernando del Moral González - El descubrimiento de las edificaciones mayas de Centroamérica por medio de la fotografía, por Arturo Aguilar Ochoa
Using Artificial Intelligence for turbulent combustion modelling: Simplifying the conventional lookup tables
No full textIn reacting flows, detailed chemistry computations are usually avoided precomputing the thermochemical quantities as functions of a reduced set of variables such as the Flamelet Generated Manifold (FGM) approach[34]. Although it mitigates the calculations of detailed chemical mechanism, the memory requirement associated to store the lookup table and retrieve the information during numerical simulations is usually large (order of Gigabytes). Thereby, extending the FGM approach in order to include other conditions requires to addother independent variables which will inevitable lead to increase the size of the lookup table. This will generate that Large Eddy Simulations (LES) cannot be performed such as is the case of the Diluted Air FGM (DA-FGM) approach developed by Xu Huang[9], limiting the simulations to Reynolds Average Navier-Stokes (RANS) approach. In this master thesis, the goal is to use Artificial Intelligence (AI)-Machine Learning (ML) techniques in order to reduce substantially the computational cost of storing lookup tables. In order to achieve this, the Artificial Neural Network (ANN) technique is used. First, a 4D FGM lookup table for hydrogen flames is simplified using the aforementioned AI technique. Then, this technique is used to replace a 6D lookup table generated using the DA-FGM approach. The accuracy and stability of the models provided by ANNs is measured by statistical indicators, providing high accurate and stable AI models. Finally, in the middle of this project, unexpected issues regarding the 4D lookup table were encountered, which lead to recreate the 4D lookup table. After studying carefully how the 4D lookup table was created, a new 4D lookup table is generated, providing excellent results and improving the AI models obtained.Mechanical Engineering | Process and Energy Technolog
Interétnicidad y salud en la costa chica de Oaxaca.
No full textTesis para optar por el grado de Maestría en Antropología Socia
La dama del perrito. Alquimia. Sistema Nacional de Fototecas: Figuraciones y signos. Num. 9 Año 3 (2000) mayo-agosto
No full textSelf-explaining and Individual Differences in Multimedia Learning
No full textabstract: Multimodal presentations have been found to facilitate learning, however, may be a disadvantage for low spatial ability students if they require spatial visualization. This disadvantage stems from their limited capacity to spatially visualize and retain information from both text and diagrams for integration. Similarly, working memory capacity (WMC) likely plays a key role in a learner's ability to retain information presented to them via both modalities. The present study investigated whether or not the act of self-explaining helps resolve deficits in learning caused by individual differences in spatial ability, working memory capacity, and prior knowledge when learning with text, or text and diagrams. No interactions were found, but prior knowledge consistently predicted performance on like posttests. The author presents methodological and theoretical explanations as to the null results of the present study.Dissertation/ThesisM.S. Applied Psychology 201
Minimum Circuit Size, Graph Isomorphism, and Related Problems
No full textWe study the computational power of deciding whether a given truth-table can be described by a circuit of a given size (the Minimum Circuit Size Problem, or MCSP for short), and of the variant denoted MKTP where circuit size is replaced by a polynomially-related Kolmogorov measure. Prior to our work, all reductions from supposedly-intractable problems to MCSP / MKTP hinged on the power of MCSP / MKTP to distinguish random distributions from distributions produced by hardness-based pseudorandom generator constructions. We develop a fundamentally different approach inspired by the well-known interactive proof system for the complement of Graph Isomorphism (GI). It yields a randomized reduction with zero-sided error from GI to MKTP. We generalize the result and show that GI can be replaced by any isomorphism problem for which the underlying group satises some elementary properties. Instantiations include Linear Code Equivalence, Permutation Group Conjugacy, and Matrix Subspace Conjugacy. Along the way we develop encodings of isomorphism classes that are efficiently decodable and achieve compression that is at or near the information-theoretic optimum; those encodings may be of independent interest.This article is "to appear" in SIAM Journal on ComputingPeer reviewedAn extended abstract of this paper appeared in the Proceedings of the 9th Innovations in Theoretical Computer Science Conference (ITCS’18)
Questions Of Collaboration, Engagement, And Belonging In Zoom And Blogs
No full textThis piece argues for a combination of synchronous (Zoom) and asynchronous (blogs) classroom activities to in an upper-division writing class, with the goal of creating a space where students connected to peers, the teacher, and their work. Via a review of literature and semi-structured interviews with students, the author argues for a learner-centered approach that allows students to have a meaningful classroom experience during the realities of teaching online during the Covid-19 crisis
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