2,927 research outputs found
Dutch Experience in Irrigation Water Management Modelling
Modeling the soil-water-crop atmosphere system to improve agricultural water management in arid zones (SWATRE); Groundwater approach to drainage design in irrigated agriculture (SGMP); Computer Program for flume and weir design (FLUME 3.0); A hydrodynamic model in the design of operational controllers for water systems (MODIS/MATLAB); Decision support simulation model for water management at a regional and national scale (SIWARE); Management of water delivery systems (RIBASIM/OMIS); A water allocation, scheduling, and monitoring program (WASAM); and Irrigation agencies, farmers and computational decision support tools
Simplex solid states of SU(N) quantum antiferromagnets
I define a set of wavefunctions for SU(N) lattice antiferromagnets, analogous
to the valence bond solid states of Affleck, Kennedy, Lieb, and Tasaki (AKLT),
in which the singlets are extended over N-site simplices. As with the valence
bond solids, the new simplex solid (SS) states are extinguished by certain
local projection operators, allowing us to construct Hamiltonians with local
interactions which render the SS states exact ground states. Using a coherent
state representation, we show that the quantum correlations in each SS state
are calculable as the finite temperature correlations of an associated
classical model, with N-spin interactions, on the same lattice. In three and
higher dimensions, the SS states can spontaneously break SU(N) and exhibit
N-sublattice long-ranged order, as a function of a discrete parameter which
fixes the local representation of SU(N). I analyze this transition using a
classical mean field approach. For N>2 the ordered state is selected via an
"order by disorder" mechanism. As in the AKLT case, the bulk representations
fractionalize at an edge, and the ground state entropy is proportional to the
volume of the boundary.Comment: 14 pages, 8 figures, minor typos correcte
Water-promoted ammonia oxidation by a platinum amine complex in zeolite HZSM-5 catalyst
In this study it was found that [Pt(NH3)(4)]HZSM-5 is an active catalyst for the oxidation of ammonia at low temperature that, in contrast with other catalysts, becomes more active in the presence of water. Furthermore, the selectivity to nitrogen was found to increase when water is presen
On agent cooperation:the relevance of cognitive plausibility for multiagent simulation models of organizations
Impact of Human Immunodeficiency Virus Infection on the Outcome of Treatment and Survival of Tuberculosis Patients in Mwanza, Tanzania.
Little is known about the outcome of tuberculosis (TB) treatment and subsequent survival of human immunodeficiency virus (HIV) infected patients treated under routine programme conditions in a developing country. We followed a cohort of HIV-positive and HIV-negative tuberculosis patients during therapy and assessed their vital and tuberculosis status 3 years after completion of treatment in Mwanza, Tanzania. Newly diagnosed and relapse tuberculosis cases consecutively registered over a 6-month period were enrolled into an epidemiological study of TB/HIV. Treatment outcome was based on information in tuberculosis treatment registers. Patients surviving treatment were assessed 3 years later by personal interview. Cause of death was determined by verbal autopsy. Of 561 patients enrolled into the study, 505 patients alive at completion of treatment were eligible for assessment at 3 years. Except for mortality, HIV infection was not statistically associated with differing treatment outcomes. At time of follow-up, the overall mortality was 19% and was associated with HIV infection (hazard ratio [hr] 3.7, 95% confidence interval [CI] 2.6-5.2) and age 35 years and over (hr 1.5, 95% CI 1.02-2.1), but not with type of tuberculosis, gender, or initial drug resistance. By life table analysis, probability of survival at 4 years was 35% for HIV-positive patients compared to 90% for HIV-negative patients. Although no relapse cases were diagnosed, verbal autopsy suggested equivalent low rates of relapse in both groups. These results demonstrate the effectiveness of the current approach to the treatment of tuberculosis patients regardless of HIV status. However, HIV-related mortality remains high both during and following completion of treatment, and further studies are needed to determine if this mortality might be reduced by simple interventions which are feasible in developing countries.\u
Optimal Control for Wind Turbine Wake Mixing on Floating Platforms
Dynamic induction control is a wind farm flow control strategy that utilises
wind turbine thrust variations to accelerate breakdown of the aerodynamic wake
and improve downstream turbine performance. However, when floating wind
turbines are considered, additional dynamics and challenges appear that make
optimal control difficult. In this work, we propose an adjoint optimisation
framework for non-linear economic model-predictive control, which utilises a
novel coupling of an existing aerodynamic wake model to floating platform
hydrodynamics. Analysis of the frequency response for the coupled model shows
that it is possible to achieve wind turbine thrust variations without inducing
large motion of the rotor. Using economic model-predictive control, we find
dynamic induction results that lead to an improvement of 7% over static
induction control, where the dynamic controller stimulates wake breakdown with
only small variations in rotor displacement. This novel model formulation
provides a starting point for the adaptation of dynamic wind farm flow control
strategies for floating wind turbines.Comment: 6 pages, 8 figures, accepted for publication for IFAC World Congress
202
Hergebruik drainwater in stellingenteelt aardbei
Bij de huidige teeltmethode kunnen een groot aantal gewassen niet meer voldoen aan de toekomstige EU richtlijn van 50 ml nitraat per liter in het grondwater. Ook het gewas aardbeien levert problemen op. Door aardbeien op stellingen te telen en het water te hergebruiken ontstaat een gesloten teeltsysteem waarin water en nutriënten optimaal worden gebruikt. Om na te gaan hoe de praktijk tegen deze ontwikkeling aankijkt is een enquête uitgevoerd
Beetle eater beheerst de aspergekever bij de oogst van groene asperges in 2010
In Canada is een grote stofzuiger die voor of achter een tractor bevestigd kan worden “Beetle Eater”
genaamd, gebruikt ter bestrijding van de coloradokever in aardappelen. Biologische telers hebben zo’n
apparaat gekocht om hem in te zetten ter bestrijding van de wortelvlieg in peen. De resultaten vielen tegen en het apparaat is na twee jaar experimenteren niet meer gebruikt.
In 2010 is de machine getest in groene asperges tegen de aspergekever op een gangbaar bedrijf in Noord - Brabant. Omdat groene asperges bij gunstige weersomstandigheden dagelijks geoogst worden, is het lastig om tegen dit insect gewasbeschermingsmiddelen in te zetten vanwege de veiligheidstermijn. Door de Beetle eater 1 of 2 keer (direct na elkaar) in te zetten worden de aspergekevers met 50 of 74% gereduceerd. De asperge oogsters merkten meteen wanneer de machine was ingezet omdat het aantal eitjes op de aspergestengels duidelijk afnam. Door de Beetle eater regelmatig in te zetten bleven het aantal afgezette eitjes op de stengels beperkt en zijn het gehele seizoen geen groene asperges bij deze teler afgekeurd en geen asperges daardoor aangemerkt als kwaliteit II. Een aandachtspunt is wel dat na iedere behandeling aspergestengels afbreken. Dit komt enerzijds omdat de rijafstand niet correspondeerde met de zuigmonden van de Beetle eater (scheelde 5 cm) en anderzijds omdat bij oudere percelen de aspergestengels verder uit het hart van de rug kunnen groeien. Door de zuigmond aan te passen (verbreden en iets te vergroten) is de verwachting dat het afbreken van de stengels beperkt wordt
Making the news interesting: understanding the relationship between familiarity and interest
News feeds are an important element of information encountering, feeding our (new) interests but also leading to a state of information overload. Current solutions often select information similar to the user's interests. However, long-term interest in one topic, and being highly familiar with that topic, does not necessarily imply an actual interest response will occur when more of the same topic is selected. This study explores how important familiarity is in predicting an interest response. In a study with 30 subjects, interest was manipulated by topical familiarity using novel stimuli from a popular news source. This study shows, within this context, familiarity is moderately important for an interest response: familiarity does indeed make the news interesting, but only to a certain extent. The results set a baseline for predicting interest during information encountering, indicating familiarity is important, but not the only influential variable a system should consider when selecting information for users
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