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System Experiments (system + experiment)
Selected AbstractsAssessment of the impact of key terrestrial observing systems using DMI-HIRLAMTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 633 2008Bjarne Amstrup Abstract Following a EUCOS decision to make an assessment of the impact on NWP forecasts of different components of the current observing systems in various combinations, a number of OSEs (Observing System Experiments) have been made by a number of NWP centres, with some running global models and some limited-area models. The Danish Meteorological Institute (DMI) carried out OSEs with the limited-area model HIRLAM. The following runs were made by DMI (two periods, one month each): (1) A baseline system (BL); (2) BL + all aircraft wind and temperature data; (3) BL + non-GUAN radiosonde winds; (4) BL + non-GUAN radiosonde temperature and wind; (5) BL + wind profiler; (6) as (4) + aircraft wind and temperature; (7) as (4) + non-GUAN radiosonde humidity; (8) as BL + all in situ data (full combined system); and (9) BL + E-AMDAR only (no ACARS and no traditional AIREPs). The lateral boundaries for these OSEs were provided by runs made by ECMWF, which was one of the centres to make OSEs with a global model. The main conclusions are that the radiosonde data are the most important data, closely followed by the aircraft data, and that aircraft data and radiosonde data are complementary and not redundant data. Furthermore the results show that it is important to have both wind and temperature profile data; wind data alone produce much poorer impact. Copyright © 2008 Royal Meteorological Society [source] Hypervideo application on an experimental control system as an approach to educationCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 1 2008Debevc, Matja Abstract Hypervideo, as an interactive tool with links within video frames, is becoming widely used in multimedia presentations for e-learning applications. Its concept of rich multimedia presentation together with temporal based link objects, gives a chance for use in engineering education courses, where many practical work and experiments are needed. In the article we present a strategy for the development and navigation of hypervideo application, to be used in engineering education. Example of magnetic suspension system experiment was built as hypervideo application. The system usability was tested with two methods, software usability measurement inventory (SUMI) evaluation and general approach to usability engineering. Test results have shown that hypervideo increases the users' motivation to work and helps students recognize, organize and present specific information. By applying some of the proposed improvements in future development, hypervideo could be a significant tool in the future of engineering education. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 31,44, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20116 [source] A test for Allee effects in the self-incompatible wasp-pollinated milkweed Gomphocarpus physocarpusAUSTRAL ECOLOGY, Issue 6 2009GARETH COOMBS Abstract It has been suggested that plants that are good colonizers will generally have either an ability to self-fertilize or a generalist pollination system. This prediction is based on the idea that these reproductive traits should confer resistance to Allee effects in founder populations and was tested using Gomphocarpus physocarpus (Asclepiadoideae: Apocynaceae), a species native to South Africa that is invasive in other parts of the world. We found no significant relationships between the size of G. physocarpus populations and various measures of pollination success (pollen deposition, pollen removal and pollen transfer efficiency) and fruit set. A breeding system experiment showed that plants in a South African population are genetically self-incompatible and thus obligate outcrossers. Outcrossing is further enhanced by mechanical reconfiguration of removed pollinaria before the pollinia can be deposited. Self-pollination is reduced when such reconfiguration exceeds the average duration of pollinator visits to a plant. Observations suggest that a wide variety of wasp species in the genera Belonogaster and Polistes (Vespidae) are the primary pollinators. We conclude that efficient pollination of plants in small founding populations, resulting from their generalist wasp-pollination system, contributes in part to the colonizing success of G. physocarpus. The presence of similar wasps in other parts of the world has evidently facilitated the expansion of the range of this milkweed. [source] Modular hardware design for distant-internet embedded systems engineering laboratoryCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 4 2009Xicai Yue Abstract A novel hardware system providing remote accessible embedded system experiments of microcontroller, digital signal processor (DSP), and field-programmable gate array (FPGA) via Internet is presented. Three newly developed hardware modules for integrating experimental boards, experimental instrumentation, and a PC workstation in the distant embedded laboratory are fully described. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 389,397, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20259 [source] Reactivity in LaGaO3/Ni and CeO2/Ni SystemsFUEL CELLS, Issue 2 2006N. Solak Abstract The reactivity in CeO2/Ni and LaGaO3/Ni systems, which are constituents of intermediate temperature solid oxide fuel cell (IT-SOFC) anodes, has been investigated both computationally and experimentally. The CALPHAD-method (CALculating of PHAse Diagrams), employing BINGSS and THERMOCALC software, was used to obtain a self-consistent set of Gibbs energy functions describing the systems. Interactions in the LaGaO3/Ni system were predicted using a thermodynamic database developed for the La-Ga-Ni-O system. Similarly, to analyze the CeO2/Ni system, the Ce-Ni-O ternary phase diagram was calculated using known thermodynamic data for binary Ce-O, Ni-O, and Ce-Ni systems. The experimental work was designed based on the calculated phase diagrams. While the La-Ga-Ni-O system experiments were conducted in air, the Ce-Ni-O system was also investigated in a reducing atmosphere. The calculated Ce-Ni-O diagram is in good agreement with the experimental results. It has been found that NiO does not react with CeO2. Extended solid solutions of La(Ga,Ni)O3, La2(Ni,Ga)O4, and La4(Ni,Ga)3O10 were found in the La-Ga-Ni-O system. Additionally, the compound LaNiGa11O19, with magnetoplumbite-type structure, has been found, which has not been reported in the literature so far. It is concluded that La2NiO4 is not chemically compatible, as a cathode material, with the LSGM electrolyte. [source] Pollen source and resource limitation to fruit production in the rare species Eremosparton songoricum (Fabaceae)NORDIC JOURNAL OF BOTANY, Issue 4 2010Xiang Shi Eremosparton songoricum (Litv.) Vass. is a rare, central Asian desert species which shows lower fruit set and seed set (<16%) than most hermaphroditic species. We hypothesized that fruit production was limited by pollen and resources. To evaluate potential fruit abortion due to pollen limitation, supplemental hand-pollination was undertaken, the mating system was investigated and the foraging behavior of pollinators was recorded. To investigate possibile resource limitation, flowers and young pods were artificially removed and fertilization were manipulated. The results showed that under natural pollination, the number of pollen deposited on the stigma greatly exceed the number of ovules per ovary. Mating system experiments showed that the species is self-compatible, but depended on pollinators to set seeds. Supplemental outcross pollination increased fruit set significantly. The most frequent effective pollinator Megachile terminate Morawitz, was observed pollinating many flowers of the same individual plant (74.5±1.3%). These results suggested that fruit production is affected by insufficient outcross pollen rather than by pollen quantity. Removal of 2/3 of the flowers and young pods led to significantly higher fruit set, as did addition of fertilizers (N,P,K: 0.025,0.05,0.013,g, N,P,K: 0.05,0.1,0.025,g) showing that reducing resource acceptors and increasing inorganic resources both helps to improve fruit set. We therefore conclude that reproductive success of E. songoricum is limited by both outcross pollen and available nutrients. [source] Characterization of the impact of geostationary clear-sky radiances on wind analyses in a 4D-Var contextTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 644 2009C. Peubey The impact of geostationary clear-sky radiances (CSRs) on 4D-Var wind analyses has been investigated by running a set of observing system experiments. Analysis scores have been calculated to measure the ability of individual satellite datasets to improve the wind analysis, starting from a no-satellite baseline. In this context, the assimilation of CSRs from the two water-vapour channels on Meteosat-9 has been found to improve the wind analysis throughout the troposphere, with the strongest signal at 300 and 500 hPa. Indeed, for the Northern Hemisphere and the Tropics, the CSR impact at these levels exceeds that of the Meteosat-9 atmospheric motion vectors (AMVs), the sampling of the latter in the assimilation being rather limited. Conversely, the impact of AMVs exceeds that of CSRs in the lower troposphere, where the latter provide very little direct information. This demonstrates the complementarity of the two datasets in the operational 4D-Var wind analysis. The mechanisms through which the assimilation of CSRs can impact wind analyses have been isolated. The dominant effect is that of humidity-tracer advection, by which the wind field is adjusted in order to fit observed humidity features via the minimization of the 4D-Var cost function. Other mechanisms, such as balance constraints and the cycling of the forecast model that links the humidity and wind variables, have been found to play a minor role. The benefit of having frequent CSR images within the assimilation window has also been demonstrated. Copyright © 2009 Royal Meteorological Society [source] Assimilation of IASI at the Met Office and assessment of its impact through observing system experimentsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 639 2009F. Hilton Abstract Observations from the Infrared Atmospheric Sounding Interferometer (IASI), onboard EUMETSAT's MetOp satellite, have been assimilated at the Met Office in global and regional numerical weather-prediction systems since 27 November 2007. Pre-operational trials of IASI assimilation in the global model during the summer of 2007 delivered a positive impact on forecasts approximately twice as large as that shown by the Atmospheric InfraRed Sounder (AIRS) on the EOS-Aqua satellite. A series of observing system experiments confirmed the relative performance of IASI and AIRS, and showed that impact from IASI is equivalent to a single Advanced Microwave Sounding Unit-A (AMSU-A) combined with a single Microwave Humidity Sounder (MHS). The results of an IASI assimilation trial for the winter of 2007 were consistent with those of the summer trial, although the impact was slightly lower overall. The assessment of impact is strongly dependent on the variables and methods chosen for verification: assimilation trials with the regional model showed similar improvements to the large-scale fields (e.g. mean-sea-level pressure and geopotential height) as seen in the global model, but no forecast impact was seen for variables such as visibility and rain-rate. © Crown Copyright 2009. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. [source] Monitoring the observation impact on the short-range forecastTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 638 2009Carla Cardinali Abstract This paper describes the use of forecast sensitivity to observations as a diagnostic tool to monitor the observation impact on the 24-hour forecast range. In particular, the forecast error is provided by the control experiments (using all observations available) of two sets of observing system experiments performed at ECMWF, a month in summer 2006 and a month in winter 2007, respectively. In such a way, the observation data impact obtained with the forecast sensitivity is compared with the observing system experiment's data impact; differences and similarities are highlighted. Globally, the assimilated observations decrease the forecast error; locally, some poor performances are detected that are related either to the data quality or to the suboptimality of the data assimilation system. It is also found that the synoptic situation can affect the measurements or can produce areas of large field variability that the assimilation system cannot model correctly. Copyright © 2009 Royal Meteorological Society [source] InP DHBT circuits: From device physics to 40Gb/s and 100Gb/s transmission system experimentsBELL LABS TECHNICAL JOURNAL, Issue 3 2009Nils Weimann The capacity of fiber-optic telecommunication systems can be increased by higher data rate signaling. We present key analog and digital circuits which find application as building blocks in future very high data rate systems. The circuits are fabricated in our indium phosphide (InP) double-heterojunction bipolar transistor (DHBT) technology. The physical properties of the InP material system, notably high breakdown and high electron mobility, enable functions that are not accessible with current silicon-based high-speed technologies, including SiGe. Device and circuit results are presented, and we report on transmission system experiments conducted with these InP DHBT circuits. © 2009 Alcatel-Lucent. [source] Managing nitrogen on the farm: the devil is in the detail,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2007Mark Shepherd Abstract Agricultural activity is a major source of nitrate in surface and ground waters. There has been a large research effort over the last 20 years to understand nitrate leaching processes and to develop ,best management practices' (BMPs) that can be adopted in farming systems to reduce losses to the wider environment. This paper reviews some of the issues relating to the development, use and adoption of these BMPs in farming systems. There is significant evidence from farming systems experiments and modelling studies that combinations of BMPs can decrease nitrate losses from agricultural land, though nothing is foolproof (the weather plays a key role in determining success). The challenges are greater in some regions (dry climate, ,leaky' soils) and in some enterprises (intensive animal farming systems). The adoption of BMPs on farms requires attention to detail and a high level of management skill, so providing advisory support to farmers is essential. Even with the progress that has been made in recent years, there is still work to do. This includes encouraging uptake on farms and dealing with potential conflicts between BMPs when they create ,pollution swapping' or where there is potential for a large economic penalty for the farmer. We also suggest that there is a need for more innovation in developing BMPs and a need to recognise that, in some situations, radical changes to farming systems may be the only solution. Copyright © 2007 Society of Chemical Industry [source] | |||||||||||||