1,366 research outputs found
Global Nonlinear Model Identification with Multivariate Splines
No full textAt present, model based control systems play an essential role in many aspects of modern society. Application areas of model based control systems range from food processing to medical imaging, and from process control in oil refineries to the flight control systems of modern aircraft. Central to a model based control system is a mathematical model of the physical system or process that is being controlled. The field of science concerned with the identification of models of physical systems is called system identification. In this thesis, a new methodology is proposed for the identification of models of nonlinear systems using multivariate simplex splines. This new methodology has the potential to increase the performance of any model based control system by improving the quality of system models. Multivariate simplex splines consist of polynomial basis functions, called B-form polynomials, which are defined on geometric structures called simplices. Every simplex supports a single B-form polynomial which itself consists of a linear combination of Bernstein basis polynomials. Each individual Bernstein basis polynomial is scaled by a single coefficient called a B-coefficient. The B-coefficients have a special property in the sense that they have a unique spatial location inside their supporting simplex. This spatial structure, also known as the B-net, provides a number of unique capabilities that add to the desirability of the simplex splines as a tool for data approximation. For example, the B-net simplifies local model modification by directly relating specific model regions to subsets of B-coefficients involved in shaping the model in those regions. This particular capability has the potential to play an important role in future adaptive model based control systems. In such a control system, an on-board simplex spline model can be locally adapted in real time to reflect changes in system dynamics. The approximation power of the multivariate simplex splines can be increased by joining any number of simplices together into a geometric structure called a triangulation. Triangulations come in many shapes and sizes, ranging from configurations consisting of just two simplices to configurations containing millions of simplices. Triangulations can be optimized by locally increasing or decreasing the density of simplices to reflect local system complexity. The new methodology was applied in the identification of a complete set of aerodynamic models for the Cessna Citation II laboratory using flight data obtained during seven test flights. In total, 247 flight test maneuvers were flown which together provided a significant coverage of the flight envelope of the Citation II. The complete identification dataset consisted of millions of measurements on more than sixty flight parameters. More than 2000 prototype spline based aerodynamic models were identified using a newly developed, highly optimized software implementation of the simplex spline identification algorithm. Using the developed methods for simplex spline model validation it was proved that the models are both accurate and of guaranteed numerical stability inside the spline domain. The identification and validation results of the simplex spline models were compared with those of ordinary polynomial models identified using standard identification methods. These results showed that the multivariate simplex spline based aerodynamic models were of significantly higher quality than the aerodynamic models based on ordinary polynomials.Control & OperationsAerospace Engineerin
Historic tree at Mission Carmel (San Carlos Borromeo de Carmelo) in Monterey, ca.1888
No full textPhotograph of the historic tree at Mission Carmel (San Carlos Borromeo de Carmelo) in Monterey, ca.1888. The tree stands at center, growing from the slope of a hill that feeds into the dry ravine at left. In the background left, the gaurd rail of a bridge can be seen.; "Viscaino hung bell on this tree and held mass in 1602 and Father Juniper Serra utilized it for the same purpose June 3, 1770 when he first landed to establish a mission for Saint Charles. [Also the boat was tied here.] The tree fell early in 1900 and the trunk was removed to the garden at rear of San Carlos Mission in Monterey. Photo made by a Mr. Adams [a photographer of Monterey about 1890] abt. 1880 and [negative] purchased from him about 1895 by C.C. Pierce". -- Unknown author
Sterkte en vervorming van waterbouwasfaltbeton (I)
No full text-Bereiding van proefstukken waterbouwasfaltbeton op lab-schaal met een constante kwaliteit blijkt tot de mogelijkheden te behoren. Bij 7% bitumen kan de verdichting vermoedelijk lichter zijn dan de standaardmethode voor wegenbouwmengsels om een holle ruimteniveau van circa 4% te bereiken. Het is de vraag of dit ook bij 6, 5% bitumen het geval kan zijn. -Het kruip- en rekonderzoek geeft als duidelijke indicatie, dat de vervorming en S-modulus mede afhankelijk zijn van het type normaalspanning. Intensiever onderzoek, mede met het oog op de spreiding in resultaten, zal moeten uitwijzen, hoe die afhankelijkheid precies is. - Bij de bezwijkproeven blijkt de sterkte mede afhankelijk van het type normaalspanning. Dit is veel minder het geval bij de resulterende vervormingen. Als gevolg van beide is toch de S-modulus sterk afhankelijk van het feit, of deze met druk- of trekspanningen is bepaald. - Bij alle proeven blijkt de grote invloed van de temperatuur en vervormingssnelheid op het vervormingsgedrag en de sterkte. -Voor een betere interpretatie van de splijtproeven is het noodzakelijk de horizontale vervormingen te meten, zodat de S-modulus kan worden vastgesteld. - Het totaal aan stijfheidsmoduli geeft een band als "mastercurve". De met drukspanningen bepaalde waarden liggen in het algemeen op een hoger niveau dan de met trekspanningen bepaalde waarden. -Voor de bepaling van het hogere stijfheidsniveau moeten dynamische onderzoeksmethoden worden gehanteerd.TAW A4 Asfalttoepassinge
A fast ethanol assay to detect seed deterioration
No full textThe most common way to test seed quality is to use a simple and reliable but time- and space-consuming germination test. In this paper we present a fast and simple method to analyse cabbage seed deterioration by measuring ethanol production from partially imbibed seeds. The method uses a modified breath analyser and is simple compared to gas chromatographic or enzymatic procedures. A modified method using elevated temperatures (40°C instead of 20°C) shortened the assay time and improved its sensitivity. The analysis showed an inverse correlation between ethanol production and seed quality (e.g. the final percentages or speed of germination and the number of normal seedlings). The increase in ethanol production was observed when cabbage seeds were deteriorated by storage under ambient conditions or hot water treatments, both of which reduced the number of normal seedlings. Premature seeds produced more ethanol upon imbibition than mature seeds. Ethanol production occurred simultaneously with oxygen consumption, indicating that lack of oxygen is not the major trigger for ethanol production
Revisions of African Moraceae (excluding Dorstenia, Ficus, Musanga and Myrianthus)
No full textIn continuation of de Ruiter’s treatment of Myrianthus and Musanga (Bull. Jard. Bot. Nat. Belg. 46: 471-510.1976), the present paper gives a revision of the African representatives of 17 genera of the Moraceae. The area studied not only consists of the African Continent, but also includes Madagascar, the Comoro Islands, the Mascarenes, the Seychelles, and the Aldabra Islands. Several new combinations are made: Antiaris toxicaria ssp. africana (Engl.) C.C. Berg, A. toxicaría ssp. africana var. usambarensis” (Engl.) C.C. Berg, A. toxicaria ssp. macrophylla (R.Br.) C.C. Berg, A. toxicaría ssp. madagascariensis (H. Perrier) C.C. Berg, A. toxicaria ssp. humbertii (Léandri) C.C. Berg, Broussonetia greveana (Baillon) C.C. Berg, Treculia africana ssp. madagascarica (N.E.Br.) C.C. Berg, and T. africana ssp. madagascarica var. sambiranensis (Léandri) C. C. Berg. Many names are brought into synonymy. Besides revising taxa, the present study aims to fill a gap in our knowledge between Asian Moraceae (studied by Corner, whose studies resulted in a new classification of the family) and the neotropical Moraceae, a subject of study by the present author. Therefore discussions about classification of the family and relationships of African Moraceae with moraceous taxa elsewhere are an essential part of the present paper
Goede bestuiving kan besdracht bij snijheester verbeteren
No full textAandachtspunten bij het gebruik van bijen voor de bestuiving van sierbesheesters. De laatste jaren hebben naast boomkwekerijen ook akkerbouwbedrijven zich toegelegd op de teelt van besdragende snijheesters. Een goede bestuiving is daarbij van groot belang voor de beszetting. Problemen ontstaan met name bij grote percelen met eenzelfde ras en bij bedekte teelten. Optimalisatie van de teeltomstandigheden moet vooral gericht zijn op het krijgen van bloemen van goede kwaliteit (voldoende nectar en stuifmeel); een goede vochtvoorziening en relatieve luchtvochtigheid zijn daarbij essentieel. Meer informatie in PPO-rapport nr. 413: M.E.C.M. Hop & C.C. Smeekens, Bestuiving van besheester
Kostenoverschrijdingen in transportinfrastructuurprojecten in Nederland: Implicaties voor besluitvorming
No full textKostenoverschrijdingen zijn een groot en aanhoudend probleem in grootschalige transportinfrastructuurprojecten. In samenwerking met het Ministerie van Infrastructuur en Milieu heeft de TU Delft onderzoek uitgevoerd naar een groot aantal projecten in Nederland en heeft het de projectprestatie in Nederland vergeleken met dat in andere landen in de wereld. Dit artikel gaat in op de implicaties van deze resultaten op 1) de huidige besluitvorming van grootschalige projecten en 2) kostenschattingen. We bevelen aan dat er in het algemeen meer aandacht wordt besteed aan kostenschattingen, en specifiek raden we aan om de methode ‘Reference Class Forecasting’ te gebruiken bij het voorspellen van de kosten omdat die vermoedelijk tot aanzienlijke betere schattingen zal leiden. Het uitgevoerde onderzoek brengt naast de onderzoeken van de Tijdelijke Commissie Infrastructuurprojecten, de commissie Elverding en de adviescommissie Versnelling en Verbetering Besluitvorming Infrastructuur nieuwe inzichten voor de besluitvorming en de projectprestatie van Nederlandse transportinfrastructuurprojecten.Infrastructures, Systems and ServicesTechnology, Policy and Managemen
Desodorante no... casa sí... efectos de frecuencia y longitud en la producción de palabras de una paciente afásica
No full textSe presentan los resultados de una investigación realizada con la paciente afásica C.C., en que se determina la incidencia de la frecuencia, la longitud fonológica y la longitud silábica en la producción de palabras de la paciente, a partir de una prueba de denominación.The author presents the results obtained in research conducted with the aphasic Costa Rican speaker (C.C.). This study addresses the incidence that frequency, as well as phonological and syllable length have when naming tests
How to decrease straddle carrier traffic risk from a routing perspective?
No full textBetween 2009 and 2012, 30 collisions between straddle carriers have been observed at APM Terminals Rotterdam. Although none of these accidents were fatal, the urgency to decrease the rate of collisions, especially the risk of a potential fatality, is apparent. The measures to prevent these collisions currently in place are developed from an equipment or human perspective rather than a process perspective, which is the expertise of the author. This is reflected by the available and researched safety measures discussed in scientific and industry literature. Collisions are directly related to the straddle carrier locations. Locations are related to a large extent to the route they take across the terminal. In order to investigate the straddle carrier collision problem from a process oriented perspective, the main research question is asked: “How to decrease straddle carrier traffic risk from a routing perspective?”Mechanical, Maritime and Materials EngineeringMarine and Transport TechnologyTransport Engineering and Logistics2014.TEL.778
Modelos de previsão da liberação de metais pesados em matrizes cimentícias produzidas com resíduos inorgânicos
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Civil, Florianópolis, 2012Apesar de certos resíduos permitirem sua valorização como material de construção, a avaliação destes produtos quanto à liberação de contaminantes quando em presença de água se faz necessária. Este trabalho teve como objetivo avaliar modelos de lixiviação de poluentes em argamassas e concretos à base de resíduos inorgânicos. Utilizando ferramenta computacional, regressões não lineares foram realizadas para avaliar a cinética de liberação dos elementos Ca, Cl, Cu, Cd, Cr, Zn e Pb de amostras de argamassas e concretos produzidos com resíduos de construção e demolição e amostras produzidas com contaminação prévia por metais pesados (CrIII, CVI, Zn, Cd, Pb). O modelo combinado de dissolução e difusão demonstrou ser o mais adequado para a Cu, Ca, Cl, Cd, Zn e o Pb. O modelo de dissolução mostrou ser adequado ao Cálcio. O modelo de difusão pura demonstrou superestimar os valores de liberação de todos os metais estudados. O fenômeno da dissolução demonstrou influenciar o ensaio de tanque (NEN7375), devendo ser considerado no cálculo da mobilidade dos metais nas matrizes cimentícias. Ainda verificou-se a influência da dimensão do agregado na lixiviação dos elementos das matrizes cimentícias.Abstract : Although certain residues permit its reuse as building material, the evaluation of such products concerning the release of contaminants when in the presence of water is necessary. This study aimed to evaluate leaching models for contaminants in mortars and concrete samples produced with inorganic wastes. Using computational tool, nonlinear regressions were performed to evaluate the release kinetics of Ca, Cl, Cu, Cd, Cr, Zn and Pb in mortars and concrete samples produced with construction and demolition waste and samples pre-contaminated with heavy metals (CrIII, CVI, Zn, Cd Pb).The combined model of dissolution and diffusion proved to be the most suitable for Cu, Ca, Cl, Cd, Zn and Pb. The dissolution model showed to be suitable for Calcium. The simple diffusion model overestimated the release of all metals studied. The phenomenon of dissolution was found to influence the Tank Test (NEN7375) and should be considered in calculating the mobility of metals in cement matrices. In addition, the influence of aggregate size on the leaching of elements from cementitious matrices was studied
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