1,086 research outputs found
Genetic and physiological characterization of seed dormancy regulation in common waterhemp [Amaranthus tuberculatus (Moq) Sauer]
Common waterhemp [Amaranthus tuberculatus (Moq.) Sauer.] is an annual plant native to the Midwest United States and is considered a troublesome weed species. The economic importance of common waterhemp is attributable to rapid population increases, the appearance of herbicide resistant biotypes, and the emergence phenology during the cropping season. Because seed dormancy levels can determine seedling emergence patterns, and the requirements necessary to remove common waterhemp seed dormancy and enhance germination are not well understood, we characterized the genetic and physiological regulation of common waterhemp seed dormancy and how seed dormancy is regulated by environmental signals such as moisture and temperature. The results indicated that seed dormancy levels in common waterhemp are highly influenced by temperature. Interactions between daily average temperatures and seed moisture reduce seed dormancy, and temperature fluctuation alleviates dormancy and triggers germination. The heritability of seed dormancy in common waterhemp is high. The heritability of genes involved in environmental signal sensing and seed dormancy regulation is more difficult to determine, but the existence and importance of these genes in seed dormancy was confirmed. In addition, the existence of intra-specific seed dormancy variation in common waterhemp was demonstrated. The evidence suggests that selection for complex seed dormancy regulatory mechanisms in common waterhemp is possible and might be one of the reasons why this weed has successfully thrived in the Midwest Region
Sensor network design for a secure electric energy infrastructure
With the increasing threat of terrorism around the world, more attention has been paid to the security of the electric transmission infrastructure. Events in countries like Colombia, which has experienced as much as 200 terrorist attacks on its transmission infrastructure per year, show the vulnerability of the power system to these kinds of events. Although it is very difficult to avoid or predict when and where these terrorist acts can occur, quick assessment of the situation can help operators to take the optimal actions in order to avoid cascading events and the consequent partial or total blackouts. Wireless sensor networks are becoming the technology of choice for sensing applications mostly due to their ease of installation and associated lower costs. This thesis proposes a novel conceptual design for an application of wireless sensor technology for assessing the structural health of transmission lines and their implementation to improve the observability and reliability of power systems. A two layers model is presented for overcoming the communication range limitations of smart sensors and two operational modes are introduced. The main goal was to obtain a complete physical and electrical picture of the power system in real time, and determine appropriate control measures that could be automatically taken and/or suggested to the system operators once an extreme mechanical condition appears in a transmission line. For evaluating the feasibility of the concept, a dispatcher training simulator (DTS) based on the energy management system (EMS) platform from AREVA T&D was used for simulating the operation of the electric power system in real time as it is monitored at an actual energy control center
Environmental control of seed dormancy, germination and seedling emergence of three weed species
Seed germination is a critical event in the success of any weed species. However, germination of weed seeds is conditioned by the presence of dormancy. Dormancy is controlled by genes as influenced by seed developmental processes and by environmental factors. We studied how chilling (12 weeks at 4 C and wet conditions), temperature, temperature fluctuation, and light quality affect the seed dormancy of common waterhemp (Amaranthus tuberculatus (Moq.) J.D. Sauer. synonymous A. rudis J.D. Sauer), giant foxtail (Setaria faberi Herrm.) and velvetleaf (Abutilon theophrasti Medicus). Also we studied how temperature requirements for seed germination can be used for analyzing seedling emergence in artificial and natural seed banks. Chilling did not affect the dormancy level of giant foxtail or velvetleaf seeds. However, common waterhemp seeds reduced dormancy level after chilling and were more responsive to temperature fluctuation and light exposure. Only common waterhemp germination was promoted by exposure to red light (660nm). There was a positive relationship between the amplitude of temperature fluctuation and common waterhemp and giant foxtail germination. Common waterhemp seeds also increased germination rate with increasing amplitude of temperature fluctuation. Temperature requirements for germination cannot alone be used to describe weed emergence in the field. Artificial seed banks showed different emergence patterns of the weed species studied compared to the natural seed banks. The large differences between seed banks were due to soil physical characteristics and seed dormancy level
Prototipo de vivienda de adobe con energías renovables: caso de estudio localidad de Raíces, Área Natural Protegida del Parque Nacional del Nevado de Toluca, Estado de México
Como una alternativa a la construcción de la vivienda, este artículo introduce una nueva tecnología para edificar un prototipo de casa de adobe con energías renovables. Se muestrauna metodología para su diseño que se establece a partir de las características de las viviendas de la localidad de Raíces, ubicada en el municipio de Zinacantepec, dentro del territorio del Parque Nacional del Nevado de Toluca, espacio natural protegido por Decreto en 1936
Cubature formulae for the gaussian weight. Some old and new rules.
In this paper we review some of the main known facts about cubature rules to approximate integrals over domains in R-n, in particular with respect to the Gaussian weight w(x) = e(-xTx); where x = (x(1); ... ; x(n)) is an element of R-n. Some new rules are also presented. Taking into account the well-known issue of the "curse of dimensionality", our aim is at providing rules with a certain degree of algebraic precision and a reasonably small number of nodes as well as an acceptable stability. We think that the methods used to construct these new rules are of further applicability in the field of cubature formulas. The efficiency of new and old rules are compared by means of several numerical experiments
Adaptive Kalman Filtering for Multi-Step ahead Traffic Flow Prediction
International audienceGiven the importance of continuous traffic flow forecasting in most of Intelligent Transportation Systems (ITS) applications, where every new traffic data become available in every few minutes or seconds, the main objective of this study is to perform a multi-step ahead traffic flow forecasting that can meet a trade-off between accuracy, low computational load, and limited memory capacity. To this aim, based on adaptive Kalman filtering theory, two forecasting approaches are proposed. We suggest solving a multi-step ahead prediction problem as a filtering one by considering pseudo-observations coming from the averaged historical flow or the output of other predictors in the literature. For taking into account the stochastic modeling of the process and the current measurements we resort to an adaptive scheme. The proposed forecasting methods are evaluated by using measurements of the Grenoble south ring
Adaptive Kalman Filtering for Multi-Step ahead Traffic Flow Prediction
International audienceGiven the importance of continuous traffic flow forecasting in most of Intelligent Transportation Systems (ITS) applications, where every new traffic data become available in every few minutes or seconds, the main objective of this study is to perform a multi-step ahead traffic flow forecasting that can meet a trade-off between accuracy, low computational load, and limited memory capacity. To this aim, based on adaptive Kalman filtering theory, two forecasting approaches are proposed. We suggest solving a multi-step ahead prediction problem as a filtering one by considering pseudo-observations coming from the averaged historical flow or the output of other predictors in the literature. For taking into account the stochastic modeling of the process and the current measurements we resort to an adaptive scheme. The proposed forecasting methods are evaluated by using measurements of the Grenoble south ring
Graph constrained-CTM observer design for the Grenoble south ring
International audienceAn important problem in traffic estimation, forecasting, and control is the reconstruction of densities in portions of the road links not equipped with sensors. In this paper, and based on ideas from Morarescu and Canudas-de Wit [2011], we use a deterministic constrained model that reduces the number of possible affine dynamics of the system and preserves the number of vehicles in the network. In particular we reformulate the idea in Morarescu and Canudas-deWit [2011] with the correct number of feasible modes, and introduce the concept of graph constrained-CTM observer, which is used to reconstruct the densities from the Grenoble south ring use case that contains 45 cells organized in 9 links, and is simulated using a calibrated AISUM micro-simulator. This work is performed in connection with HYCON2 traffic show case (www.hycon2.eu), and with the Grenoble Traffic Lab (GTL) (http://necs.inrialpes.fr/pages/reseach/gtl.php)
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